Synaleve is a South African combination painkiller containing paracetamol, codeine and doxylamine. It is used for moderate pain that plain paracetamol is not controlling — back pain, muscular pain, severe headache and post-injury pain. Because it contains codeine it causes drowsiness, is not for long-term use, and is controlled at the pharmacy counter.

What is Synaleve?

Synaleve is a capsule containing three active ingredients working together:

Paracetamol, an analgesic that relieves pain and reduces fever.
Codeine phosphate, an opioid analgesic for moderate pain.
Doxylamine succinate, a sedating antihistamine included for its muscle-relaxant and calming effect.

That combination is why it is stronger than a plain paracetamol product such as Donapan, and also why it carries cautions that plain paracetamol does not.

Synaleve is a Schedule 6 medicine in South Africa. That is a tighter control than most painkillers on a pharmacy shelf, and it reflects the codeine content. It requires a prescription and is dispensed under a pharmacist’s supervision.

Related products exist under similar names with slightly different formulations. Check the active ingredients on your own pack rather than assuming they match.

What is Synaleve commonly used for?

Synaleve is prescribed for moderate pain — the level where simple analgesics are not enough but stronger opioids are not warranted. Common reasons include:

Lower back pain and muscular pain, where the muscle-relaxant effect of the doxylamine component is part of the intention.
Severe headache, when paracetamol alone has not worked.
Pain after injury, such as a sprain or strain.
Post-operative or post-dental pain, for a defined short period.
Period pain that is not responding to simpler treatment.

It is intended for short-term use. That is not a formality: codeine causes both tolerance and dependence with continued use, and it is a well-documented problem in South Africa, where codeine-containing products have historically been easy to obtain. Taking it regularly for weeks changes it from a helpful medicine into a problem in its own right.

It also causes medication-overuse headache — a headache caused by the painkiller itself, which drives further use. If you are taking it for headache more than a couple of days a week, that possibility is worth raising with a doctor.

How Synaleve fits into this medicine category

Within pain and inflammation medicines, Synaleve is a compound analgesic — a combination product rather than a single ingredient.

That places it a step above plain paracetamol and, in a different direction, alongside rather than above anti-inflammatories. An NSAID such as diclofenac reduces inflammation, which Synaleve does not; Synaleve adds opioid pain relief and sedation, which an NSAID does not. Which suits a given problem depends on whether inflammation is driving the pain.

Corticosteroids such as prednisone are different again, prescribed as courses for inflammatory conditions rather than as painkillers.

You can see how the groups relate on the pain, inflammation and musculoskeletal medicines hub.

What to check before using Synaleve

Check every other medicine you are taking for paracetamol. Synaleve already contains it. Adding a separate paracetamol product, or a cold and flu preparation containing it, means taking it twice — the most common route to serious accidental overdose. Read the active ingredients on everything.

Do not drive or operate machinery until you know how it affects you. Codeine and doxylamine both cause drowsiness, and the combination is more sedating than either alone. The effect can persist into the next morning.

Speak to your pharmacist or doctor before use if:

You have breathing problems, including asthma, COPD or sleep apnoea. Opioids suppress breathing.
You have liver or kidney disease.
You have a history of dependence on any substance.
You have glaucoma, an enlarged prostate or urinary retention — the doxylamine component matters here.
You have constipation or bowel problems. Codeine reliably causes constipation.
You are pregnant or breastfeeding. Codeine passes into breast milk and is generally avoided.
The medicine is for anyone under 18, and particularly after tonsil or adenoid surgery, where codeine is contraindicated.
You take other sedating medicines, including sleeping tablets, anxiety medicines or antihistamines.

Possible cautions and when to ask a pharmacist or doctor

Alcohol adds to the sedation and to the risk of suppressed breathing. Avoid it while taking Synaleve.

Do not take it for more than three days without medical advice. This is the standard guidance for codeine-containing painkillers, and it exists because dependence develops faster than people expect.

Watch for dependence. Needing it more often, taking more than directed, feeling unwell without it, or finding reasons to keep a supply are all signs worth discussing with a doctor. Help is available, and this is common enough that no one will be surprised.

Expect constipation, and drowsiness, dry mouth and nausea. Constipation is close to universal with codeine and worth planning for on anything beyond a very short course.

Stopping after prolonged use can cause withdrawal — restlessness, sweating, aches, difficulty sleeping. If you have been taking it regularly for a long period, ask a doctor how to stop rather than stopping abruptly.

Seek urgent medical attention for slow or shallow breathing, extreme drowsiness or difficulty waking, or if you suspect an overdose — and remember that a paracetamol overdose produces no early symptoms while causing liver damage. Go to an emergency department with the packaging rather than waiting.

Related medicine guides

Frequently asked questions

What is Synaleve used for? Moderate pain that simple painkillers are not controlling — back and muscular pain, severe headache, and pain after injury or a procedure. It is intended for short-term use.

Does Synaleve contain codeine? Yes. It contains paracetamol, codeine phosphate and doxylamine succinate, which is why it is a Schedule 6 medicine and why it causes drowsiness.

Can I drive while taking it? Not until you know how it affects you. Both the codeine and the doxylamine are sedating, and drowsiness can carry into the following day.

How long can I take it for? No more than three days without medical advice. Longer use risks dependence and medication-overuse headache.

Can I take other painkillers with it? Not another paracetamol product — Synaleve already contains it. Ask your pharmacist before combining it with anything else.

Is it safe in pregnancy or while breastfeeding? Codeine-containing products are generally avoided in both. Speak to your doctor about alternatives.

What Is Synaleve Used For?